20884640 has 96 divisors (see below), whose sum is σ = 58423680. Its totient is φ = 6902784.

The previous prime is 20884603. The next prime is 20884649. The reversal of 20884640 is 4648802.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 20884597 and 20884606.

It is not an unprimeable number, because it can be changed into a prime (20884649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32159 + ... + 32801.

It is an arithmetic number, because the mean of its divisors is an integer number (608580).

Almost surely, 2^20884640 is an apocalyptic number.

20884640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20884640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29211840).

20884640 is an abundant number, since it is smaller than the sum of its proper divisors (37539040).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20884640 is a wasteful number, since it uses less digits than its factorization.

20884640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694 (or 686 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 32.

The square root of 20884640 is about 4569.9715535220. The cubic root of 20884640 is about 275.3863000748.

It can be divided in two parts, 208 and 84640, that added together give a palindrome (84848).

The spelling of 20884640 in words is "twenty million, eight hundred eighty-four thousand, six hundred forty".